Means for diluting combustible gas and the like



Aug. 28, 1956 w. L. MORRISON 2,760,342

MEANS FOR .DILUTING COMBUSTIBLE GAS AND THE LIKE Filed Aug. 20, 1954 3Sheets-Sheet 1 Aug. 28. 1956 w. L. MORRISON 2,760,342

MEANS FOR DILUTING COMBUSTIBLE GAS AND THE LIKE Filed Aug. 20, 1954 2Sheets-Sheet 2 by Parker 8. Carter ATTORNEYS United States Patent NIEANSFOR DILUTING COMBUSTIBLE GAS AND THE LIKE Willard L. Morrison, LakeForest, 111., assi nor, by mesne assignments, to Constock Liquid Methane@Corporation, New York, N. Y., a corporation of Delaware ApplicationAugust 20, 1954, Serial No. 451,272

8 Claims. (Cl. 62*1) My invention relates to the method and apparatusfor safely wasting gases to atmosphere.

One object of my invention is to provide a method and apparatus forsafely wasting the combustible gas evaporated from such a cold boilingliquid as liquefied methane when such a liquid is stored atapproximately atmospheric pressure.

Circumstances can occur when the rate of evaporation resulting fromambient heat will be greater than the gas demand. Under theseconditions, it is essential that, in order to maintain the pressure inthe storage tank below a safe limit adjacent atmospheric, the gas besafely wasted.

The tank and system will be designed to hold the liquid and to maintaina pressure slightly above atmospheric, such that the evaporated gas willfiow out as desired; for example, five pounds gauge. Any pressure abovethat is dangerous, and to prevent development of excessive pressure thegas must be released by discharge to atmosphere.

Since the gas is combustible and, when mixed with the right amount ofair, will produce an explosive mixture,

it is essential that the excess gas as discharged from the tank bediluted with a suitable solvent in such proportions that a diluteincornbustible mixture results for discharge to atmosphere.

I propose to provide the volume of air necessary to dilute the gas to asafely lean mixture, by using the excess gas as it is discharged fromthe tank as a motive fluid in an expansion engine to compress or impelambient air for mixing with the gas exhausted from the turbine.

Other objects will appear from time to time throughout the specificationand claims.

My invention is illustrated more or less diagrammatically in theaccompanying drawings, wherein:

Figure l is a plan view of a vessel and storage tank to which myinvention is applied;

Figure 2 is a diagrammatic layout of a modified form of the dischargeand dilution means when applied to a tank on shore;

Figure 3 is a diagrammatic layout of a further modified form of myinvention;

Figure 4 is a diagrammatic layout of a further modified form.

Like parts are indicated by like characters throughout the specificationand drawings.

1 is a water-borne vessel, 2 an insulated tank carried thereby adaptedto contain at approximately atmospheric pressure a mass of cold boilingliquid, for example, methane or other liquefied petroleum gas. 3 is anengine, preferably an internal combustion engine, adapted to propel theboat. 4 is a gas supply pipe leading from the tank 2 to the engine 3. '5is a valve for control of gas flow to the engine. 6 is a pressure reliefpipe leading from the tank 2 to a pressure relief valve 7. 8 is a gasdischarge pipe leading from the pressure relief valve to a turbine 9. 16is a turbine exhaust pipe leading to the mixing nozzle 11. The turbine 9drives a compressor 12 which draws in air and discharges it through theair duct 13 to the mixing nozzle 11 so that the pressure of the gasdischarged through the pressure relief valve actuates a turbine tocompress air and discharge it for mixing with the exhaust gas from theturbine in the pressure nozzle with the waste gas.

Figure 2 illustrates my invention applied to a tank 12 on shore; 1'3 isa gas supply pipe controlled by valve 14 for usual discharge of the gasto point of use. The pipe 6, pop valve 7, pipe 3, turbine 9, andcompressor 12 are just as in Figure l, but turbine exhaust pipe 15 andcompressor exhaust pipe 16 join before they discharge into mixing nozzle1-7.

In the modified form of Figure 3, the pop valve 18 carries an actuatingarm .19 which, as the pressure increases and the valve is just about toopen, contacts the pad 26 on switch arm 21 to close contact 22 to closean electrical circuit from a suitable source of power at 23 throughconductor 24, contact 22, conductor 25, solenoid 26, conductor 27, backto power source 23.

Solenoid 26 opens valve 28 to release a shot of high pressure gas,preferably CO2, from pressure bottle 29 through pipe 3:) and pipe 31 toturbine 19. This shot of high pressure gas starts the turbine spinningso that when the gas from tank 2 or 12 reaches the turbine the inertiaof turbine compressor combination will have been overcome and no delayin the discharge of air for mixture with the gas exhausted from theturbine will occur.

As the valve 18 and arm 19 complete their movement to open position,switch .21 will open so gas from tank 29 will not be wasted. The sameeffect will occur as the valve closes so the CO2 will in another shotmix with the as and insure purging of the system after the gas pressureis shut off.

In the modified form of Figure 4, as the valve 18 opens, arm 19 willclose switch 39 and hold it closed as long as valve 18 is open; thiscloses a circuit from power source 31 through conductor 32, switch 30,conductor '33, electric motor $4, conductor 35, to power source 31 somotor 34 will assist gas pressure in turbine 9 to compress or dischargeair for mixing with the gas.

The details of the turbine, compressor, nozzle and relief valve are nothere illustrated since they are conventional and their details form nopart of the present invention.

For example, if a normal desired pressure in the tank is two poundsgauge and five pounds is safe, the relief valve will be set to blow offat five pounds, but it will also be set to remain wide open until thepressure drops to two pounds. Thus, between two and five pounds gauge,the valve will be wide open and the turbine will receive the fulldischarge of relief gas. When the turbine operates the compressor, theexhaust gas discharged to the mixing nozzle will be discharged at theexhaust pressure of the turbine, preferably atmospheric, and will therebe mixed with an adequate supply of air to insure an air-gas mixture solean as not to support combustion.

The relief valves 7 and .18 are the usual type of pop valves which openwhen the discharge pressure is reached and remain open until a desiredpressure drop occurs and then close at a pressure substantially belowthe opening pressure.

The velocity of the combined gas and air column discharged from themixing nozzle will preferably be greater than the rate of flamepropagation in a combustible methane gas mixture at atmosphericpressure.

The usual safeguards in the gas pipe itself to prevent flame propagationwill be provided; for example, a screen embodying the Davey miners lampprinciple.

Iclaim:

1. A safety device for discharge of combustible gas under pressure fromstorage to atmosphere including a discharge passage, a pressure reliefvalve therefor adapted to open when a predetermined maximum, and toremain open until a predetermined minimum pressure has been reached, anexpansion engine adapted to be driven by the gas discharged through thevalve, a blower driven by the expansion engine adapted'to discharge acolumn of air, means for mixing the air with the gas discharged from theexpansion engine and discharging the mixture to atmosphere, meansseparate and apart from the discharged gas for commencing bloweroperation immediately before admission of discharged gas to theexpansion engine and for continuing blower operation for a short periodafter the gas is discharged to the said expansion engine.

2. A safety device for discharge of combustible gas under pressure fromstorage to atmosphere including a discharge passage, a pressure reliefvalve therefor adapted to open when a predetermined maximum, and toremain open until a predetermined minimum pressure has been reached, anexpansion engine adapted to be driven by the gas discharged through thevalve, a blower driven by the expansion engine adapted to discharge acolumn of air, means for mixing the air with the gas discharged from theexpansion engine and discharging the mixture to atmosphere, meansseparate and apart from the discharged gas for commencing bloweroperation immediately before the valve opens.

3. A safety device for discharge of combustible gas under pressure fromstorage to atmosphere including a discharge passage, a pressure reliefvalve therefor adapted to open when a predetermined maximum, and toremain open until a predetermined minimum pressure has been reached, anexpansion engine adapted to be driven by the gas discharged through thevalve, a blower driven by the expansion engine adapted to discharge acolumn of air, means for mixing the air with the gas discharged from theexpansion engine and discharging the mixture to atmosphere, said meansincluding a carbon dioxide gas bottle, a control valve therefor, aconnection between it and the engine, means associated with the reliefvalve responsive to the pressure of the combustible gas for opening thecontrol valve for a suflicient length of time before the relief valveopens to discharge a shot of carbon dioxide under pressure into theengine to start its operation.

4. A safety device for discharge of combustible gas under pressure fromstorage to atmosphere including a discharge passage, a pressure reliefvalve therefor adapted to open when a predetermined maximum, and toremain open until a predetermined minimum pressure has been reached, anexpansion engine adapted to be driven by the gas discharged through thevalve, a blower driven by the expansion engine adapted to discharge acolumn of air, means for mixing the air with the gas discharged from theexpansion engine and discharging the mixture to atmosphere, supplementalmotor means adapted to drive the blower, means associated with therelief valve responsive to the pressure of the combustible gas foractuating the supplemental motor during the time that the pressurerelief valve is open.

5. Means for the safe discharge of a combustible gas under pressure froma container into the atmosphere including a discharge passage incommunication with the container and having a discharge opening throughwhich the combustible gas is exhausted into the atmosphere,

means operative in response to the movement of gas through the dischargepassage for displacement of air from the atmosphere into the dischargepassage, means for admixture of the air with the gas in the dischargepassage prior to exhaust into the atmosphere, and means separate andapart from the discharged gas for operation of the air displacementmeans responsive to the release of gas from the container into thedischarge passage for operation thereof prior to exhaust of the gas intothe atmosphere whereby the air becomes admixed therewith prior to theexhaust of the gas into the atmosphere.

6. Means for the safe discharge of a combustible gas under pressure froma container into the atmosphere comprising a discharge passage, apressure relief valve adapted to open when a predetermined maximum andto remain open until a predetermined minimum pressure has been reachedin the container, means operative in response to the movement of gasthrough the discharge passage for displacement of air from theatmosphere into the discharge passage, means for mixing the air with thegas prior to exhaust from the discharge passage, and other meansresponsive to the opening of said relief valve for operation of the saidan displacement means for causing displacement of air into the dischargepassage in advance of the passage of gas therethrough for admixturetherewith prior to exhaust of the gas into the atmosphere.

7. Means for the safe discharge of a combustible gas under pressure froma container into the atmosphere comprising a discharge passage, apressure relief valve adapted to open when a predetermined maximum andto remain open until a predetermined minimum pressure has been reachedin the container, means operative in response to the movement of gasthrough the discharge passage for displacement of air from theatmosphere into the discharge passage, means for mixing the air with thegas prior to exhaust from the discharge passage, and other meansresponsive to the opening and closing of the relief valve for efiectingoperation of the said air displacement means to cause displacement ofair prior to and after the exhaust of gas through the discharge opening.

8. Means for the safe discharge of a combustible gas under pressure froma container into the atmosphere comprising a discharge passage, a bloweroperative in response to the movement of gas through the dischargepassage for displacement of air from the atmosphere into the dischargepassage, means for mixing the air with the gas in the discharge passagefor exhausting the mixture to the atmosphere, and means responsive tothe exhaust of gas from the container into the discharge passage forcommencing operation of the blower in advance of passage of the gas intothe atmosphere for admixture of air with the gas prior to its exhaustinto the atmosphere.

References Qited in the file of this patent UNITED STATES PATENTS262,185 Johnson et al Aug. 1, 1-882 1,583,621 Steinberg May 4, 19262,332,227 Jackson Oct. 19, 1943 2,507,380 Morrison May 9, 1950 2,543,653Woog Feb. 27, 1951 2,552,472 Whidden May 8, 1951

